Resin curing



Uct. 25, 1966 R. D. SCHMITZ 331,515

RESIN CURING Filed Jan. 51, 1963 Res/n which cures:

(a) only at elevated temperature (12) faster at elevated temperature lmbed heated finely divided, particles -Q- sol/d, chemical/y in inert material resin Cured res/n INVENTOR.

Robert D. Schm/tz United States Patent Ofifice 3,231,515 Patented Oct. 25, 1966 3,281,515 RESET (3G Robert D. Schmitz, Burlingame, Calif, assignor to Hodges tlhernicalls Qoinpany, a corporation of California of castings, the particulate matter may contribute to the strength and/ or wear resistance of the finished article.

The particles which can be employed may be ordinary sand or gravel or can be any other material which is piled Jan. 1 19 3 Sela 255 179 5 capable of conveying heat to the resin and which does not 12 Claims. ((111. 264-236) adversely react chemically therewith. Thus, in addition to sand and gravel, glass chips, ceramic particles, marble This invention relates to a method of curing a r s or limestone chips, roofing granules, metal turnings, filings and more Particularly relates o curing a resin wherein or spheres, reflective glass beads and the like can be the cure is initiated or accelerated by heat supplied by employed. applying to the resin small heated particles of a chemically In some instances, the particulate material is merely inert substance. sprinkled onto the surface of a freshly coated resin article. Many resin systems are used industrially in applications In other instances, the particles are applied with force, wherein it iS desirable to accelerate the cure of the resin such as through conventional sandblasting equipment, by the application of heat, while other resin systems r 15 which is particularly valuable when a thick resin coating quire the application of heat in order to cure the resin. is to be treated or when the surface is vertical. In some In many instances it is impractical to heat the article instances, it is practical to cover the surface to be coated directly, as the article may have been treated so that it is with the heated particles and then apply the resin over desirable to supply the heat in some other manner. For the particles. In the making of castings, a mold may be instance, in preparing resin-coated wood panels, the wood filled with heated particles and the liquid resin poured in is a poor conductor of heat and it would be difficult to or the mold may first be partly filled with the liquid resin heat the panel to hasten the cure. Further, the wood and the heated particles then poured into the mold. might char if it were heated to a temperature high enough It has been found that the particle size is not critical to initiate or materially increase the rate of cure. In other and that various sizes of solid material can be used. Howinstances, such as when resins are used as paving maever, the material should not be in the form of fine powder terials, it would be completely impractical to attempt to since it might drift rather than entering the surface of the heat the substrate to hasten or initiate the resin cure. In resin, would tend to cool unduly on the contact of air, still other instances such as in the manufacture of molded and would be difficult to Wet with the resin. articles, and particularly articles having a thick cross sec- For the purpose of the present invention, resin systion, it is difficult to heat the resin in a uniform manner. tems which may be cured in accordance with the present In accordance with the present invention, it has been invention have been classified as follows: found that a resin can be cured and/ or that the cure time Type lrfiSystems which will normally cure at room of the resin can be materially decreased if the resin is temperature, but can be accelerated with heat. treated with small heated particles of a solid material. Type II.-Reactions which essentially take place only This is highly advantageous from several standpoints. If at elevated temperatures. a purely industrial process is being carried out wherein Type III.Elevated temperatures cause a reaction (usuwood, glass or metal panels are being coated with a resin, ally decomposition or dissociation) which releases a reacthe process time can be greatly decreased. In other intive agent, which in turn reacts with the resin. Here, of stances, the utility of the resin is greatly increased since course, the reactive agent itself may be the resinous backif a highway is being treated with a resin, it may be out bone and may comprise the majority of the film. of service for long periods of time if the resin is allowed Type IV.A physical change takes place at elevated to cure at ambient temperature. This is particularly true temperatures (melting, solvating, etc.). when a relatively thick layer is being applied. The sole figure of the drawing is a flow diagram illus- In addition to causing the cure or decreasing the cure trating the method of carrying out the present invention. time, the use of the particulate matter in coating applica- The following working examples illustrate various emtions has certain other advantages. In many instances, bodiments of the invention. particles can be such that they give a decorative textured Examples 1 and 2 are typical of the Type I system and surface to the material being treated. In other instances, in these examples a resin and catalyst were used made up particles contribute to the wear resistance and anti-skid as follows:

RESIN Parts by Weight Ingredient N t Function gii j: bri a ifiitiii eiififii iiifiiunsrj f5$1infi. base) n n Bentonite clay Thixotroping Agent, Modepoxun Triphenyl phosphate Accelerator. T tanox RA- Titanium Dioxide Pigment White Pigment. Mistron EGO-75-. Talc Pigment Inert Pigment.

CURING AGENT Ingredient: Parts by Weight Epon Curing Agent U 25 Dow Curing Agent QXZ 654.1 27 Gersamide 125 8.6

DMP 30 0.2

A1l but DMP are primary and secondary amine resinous curing agents which react with and cross link the epoxy resin. DMP is an accelerator,

In each instance, thirty-five parts of the resin were used with 6.5 parts of the curing agent.

Example 1.The resin and curing agent were mixed in the proportion stated above and a plywood panel was immediately coated to a thickness of 0.016 inch. The film was immediately covered with No. 4 sandblasting sand heated to 300 F. The sand was applied approximately to /2 inch thick. After standing five minutes the film was set, and it was impossible to pry the coarse sand loose from the panel. When a second piece of plywood was placed over the treated plywood and the weight of about 150 pounds applied and the second piece twisted, the aggregate did not move.

Example 2.The above experiment was repeated except that the sand was heated to 250 F. Here the coating set hard in ten minutes and the aggregate could not be moved when subjected to twisting under a second piece of plywood as was noted in Example 1. A control panel was treated in exactly the same manner except that the sand was at room temperature (67 F.) and was still soft after two hours; after three hours the material was beginning to set but could still be moved and even after four hours the sand could be pryed out of the panel.

In the above examples, the sand was No. 4 sandblasting sand of which 72% is 18 to 8 mesh, 27% is A to V inch in diameter and 1% is less than 18 mesh. When the experiments were repeated using No. 2 sandblasting sand, most of which passes through an 18 mesh screen, the results were substantially the same.

Example 3.The following example also represents a Type I system. In this system, a polyester resin mixture was made in accordance with the composition set forth in Table I. The resin base and initiator were mixed in the proportions stated in the table and a plywood panel was coated to a thickness of approximately 0.015 inch. The film was immediately covered with No. 4 sandblasting sand heated to 280 F. A thermocouple wire stapled to the plywood panel showed that the temperature of the plastic near the surface of the plywood rose almost immediately to 204 F. In 17 minutes, the resin had cured to a hard mass and the temperature was down to 110 F. A control film of the same material applied in the same manner but Without the heated sand was still soft after three hours.

Examples 4 and 5.The following two examples are of Type II systems. A high molecular wight hydroxylcontaining epoxy resin mixed with a phenol-formaldehyde resin and hexamethoxymethylmelamine was employed. The epoxy resin was employed to function as a high molecular weight polyol rather than as an epoxy. It is believed that the cure mechanism is a polyether formation between the hydroxyl groups of the epoxy resin and the methylol or methylated methylol groups. The compositions of the two examples are given in Tables II and III. In each instance, a film of the resin was cast on glass at room temperature to give a film thickness of trifluoride monoethylamine.

about 0.015 inch. The solvents were allowed to evaporate and then the coatings were covered with hot No. 4 sandblasting sand. The initial temperature in each instance, measured by thermocouple, was 400 F. and in 20 minutes the temperature had gone down to 194 F., at which time both systems were cured.

Examples 6 and 7.-These examples are typical of the Type III systems, and in one case an epoxy resin was cured with dicyandiamide and in the other with boron The compositions are set forth in Tables IV and V and in each instance a film 0.015 inch was cast on glass and heated sand applied thereto. Both of these systems were successfully cured, reaching an initial temperature of 560 F. Control panels were also made up, but without sand, and the the system are set forth in Table VI. Two films of the mixture on glass were made, giving an initial film of 0.006 inch which in theory should give a dry ultimate film of 0.002 inch. On the first film, reflective glass beads were sprinkled which were at room temperature. Both films were then allowed to dry at room temperature for two days with no evidence of curing. The second film was then sprinkled with heated reflective glass beads having a temperature of about 500 F. After 16 minutes, the film was fully cured. The film which had been treated with glass beads at room temperature was then immersed in toluene for 10 minutes, whereupon it became very soft. The film which had been cured with the reflective glass beads was immersed in toluene for 48 hours and was not as soft as the film which had been immersed in toluene for 10 minutes.

Example 9.-A plastisol of polyvinyl chloride is a typical example of a Type IV system. The composiiton used is set out in Table VII. Two films 15 mils thick were formed, one on glass and one on plywood. Both films were covered with hot aggregate at a temperature of about 400 F. After 10 minutes, the temperature had dropped to 208 F. and both films were fully cured.

Preferably, the solid material should be heated to a temperature of at least 200 F. since at lower temperatures the decrease in curing time is insuflicient to ordinarily make the process worthwhile. Generally speaking, higher temperatures are preferred but if the substrate is plywood or a similar material which tends to gas or 0 char when heated, the temperature should be held to TABLE I.COMPOSITION OF POLYESTER FILM stable until the initiator is added): Methyl ethyl ketone peroxide N o. 60.

Ingredient Parts by Nature Function Weight Ester Mixture:

Polyester PEI-300 100 styrtiilie Solution of Unsaturated Polyester Reactive base.

res Titanium Dioxide 12.45 Titanium dioxide White pigment. Bentone 27 2. 41 Quaternary ammonium bentonite Thixotropie agent.

0.12 Dispersing agent. Methyl Alcohol 0. 12 Methyl alcohol Used to wet Bentone 27. ctfvlfaltl naphthenate 6% Cobalt 1.0 Cobalt naphthenate Accelerator.

e a Initiator (This composition is fairly O. 5 Solution of Methylethyl ketone peroxide active.

TABLE II.-COMPOSITION OF HEXAMETHOXYMETHYLMELAMINE: EPOXY RESIN FILM Ingredient Parts by Nature Function Weight Titanium Dioxide 13. 46 Titanium dioxide White Pigment. Epon 1007 (Shell Oil Co.) 11. 44 Essentially a high molecular Weight diepoxide Resinous base.

prepared from bisphenol-A and epichlorohydrin. Cymel 300 (Am. Cyanamid Co.) 2.0 Hexamethoxymethylmelamine Co-reactant. Catalyst 1010 (Am. Cyanamid Co.) 0.15 Proprietary Catalyst. Solvents 10.0 Mixed aromatics and ketones Solvent.

TABLE III-COMPOSITION OF PHENOL FORMALDEHYDE: EPOXY RESIN FILM Ingredient Parts by Nature Function Weight Titanium Dioxide 13. 46 Titanium dioxide White pigment.

Epon 1007 See Table II Reactive resinous base.

'ethylon 75108 (General Electric Co.). 36 Essentially a mixture of the allyl ethers of Co-reactant.

mono, di, and tri, methylol phenols; the last predominating.

Phosphoric acid 0. 45 H3P04 Catalyst. Solvents 7.0 Mixed aromatics and ketones Solvent.

TABLE IV.--COMPOSITION OF EPOXY DICYANDIAMIDE RESIN FILM Ingredient Parts by Nature Function Weight Epon 828 (Shell Oil Co.) 17. 2 Diglycidyl ether of bisphenolA Resinous base. Epon 830 (Shell Oil Co.). 10.8 Slightly higher molecular weight of above Resinous base. Titanium Dioxide 23. 9 Titanium dioxide White pigment. Mistrom H G0 75... 4 Talc (Magnesium Silicate) Inert pigment. Bentone 38. 4 Quaternary ammonium bentonite Thixotropic agent. Lamp Black 0. O8 Lamp Block (carbon) Black pigment. solution of dicyandiarnide in di- 8. 4 a Crystalline curing agent in met)hylformamide (guanidinc-l cysolution ano Actually dicyandiamide decomposes into products which cure the Epoxy Resin.

TABLE V.COMPOSITION OF EPOXY BORONTRIFLUORIDE RESIN FILM Ingredient Parts by Nature Function Weight Epon 828 13. O Diglycidyl ether of bisphenol-A Resinous base. Epon 830. 22. 8 Slightly higher molecular weight of above. Resinous base. Titanium dioxide. 18. 1 Titanium dioxide White pigment. Mistrom HGO 75. 3. 2 Talc (Magnesium Silicate) Inert Pigment. Bentone 38 3. 2 Quaternary ammonium bentonite. Thixotropic agent. Lamp Black 0. 06 Lamp Black (carbon) Black pigment. Epon curing agent BF 1. 8 Borontrifluoride monoethylami Curing agent.

Actually BFaINHgCHgCHg dissociates forming BF and CZHBNHZ, both of which cure the Epoxy Resin (predominating reaction in BF: Epoxy.)

TABLE VI.-COMPOSITION OF EPOXY ISOCYANATE FILM Ingredient Parts by Nature Function Weight Titanium Dioxide 13.46 Titanium dioxide White pigment. Epon 1007 6. 07 See Tables II and III Reactive Resinous base. Mondur S (Mobay) 7. Phenol blocked isocyanate prepolymen. Co-reactive Resinous base. Solvents 12. 92 Mixed aromatics ketones and esters Solvent.

TABLE VII.COMPOSITION OF PLASTISOL FILM Ingredient Parts by Nature Function Weight QYKV-Z (Union Carbide) 46. 5 High molecular weight 100% Polyvinyl chlo- Resin.

ride resin plastisol grade.

Flexol Plasticizer DOP 34. 9 Di-(Z-ethylhexyl)phthalate Plasticizer. Titanium Dioxide 9. 3 Titanium dioxide White pigment. Arofiint system 505 Component 303 x 90 9.3 Epoxidized/soya oil 90% in xylene. Stabilizer.

(Archer Daniels Midland Company). Cabosil M-5 a. 1. 0 Colloidal silica Thixotropic agent.

I claim: contact with a finely divided, heated, solid chemically 1. The process of curing a resin which can only be inert material. cured at elevated temperatures and which cures at faster 2. The process of curing a resin which cures at room rates at elevated temperatures than at room temperature temperature but which cures at a faster rate at elevated comprising bringing the resin into intimate embedded temperatures comprising bringing the resin into intimate embedded contact with a finely divided, heated, solid chemically inert material.

3. The process of curing a resin, which resin cures only at elevated temperatures, comprising bringing the resin into intimate embedded contact with a finely divided, heated, solid chemically inert material.

4. In the process of curing a resin, which resin cures by means of a reactive reagent which is released at an elevated temperature, comprising bringingsaid resin into intimate embedded contact with a finely divided, heated, solid chemically inert material.

5. The process of curing a resin system, said resin system comprising a mixture wherein a physical change takes place only at an elevated temperature, causing the resin to cure, comprising bringing the resin system into intimate embedded contact with a finely divided, heated, solid chemically inert material.

6. The process of claim 1 wherein the finely divided material is heated to a temperature of at least 200 F.

7. The process of claim 1 wherein the finely divided solid material is sand.

8. The process of claim 1 wherein the finely divided solid material is heated glass reflective beads, which beads are only partially imbedded in the resin.

9. The process of making a molded article utilizing a resin which can only be cured at elevated temperatures and which cures at a faster rate at elevated temperatures than at room temperature comprising at least partially filling a mold with a finely divided, heated, solid chemically inert material and filling the remaining portion of said mold with said resin.

10. The process of making a molded article utilizing a liquid resin which can only be cured at elevated temperatures and which cures at a faster rate at elevated temperatures than at room temperatures comprising at least partially filling a mold with said resin and then depositing on top of said resin and embedding therein a finely divided, heated, solid chemically inert material.

11. The process of making a coated panel comprising applying to said panel a thin coating of a resin which cures only at elevated temperatures and which cures at a faster rate at elevated temperatures than at room temperature, and applying to the surface of said coated panel a finely divided, heated, solid chemically inert material.

12. The process of claim 11 wherein said material is sand.

References Cited by the Examiner UNITED STATES PATENTS 2,554,356 5/1951 Beare 264317 2,638,523 5/1953 Rubin M 264259 XR 2,847,391 8/ 1958 Wheeler.

2,948,201 8/1960 Nagin et al.

2,948,930 8/1960 Herbst 264l28 XR 3,072,968 1/1963 Watson et al. 264347 XR ALEXANDER H. BRO'DMERKEL, Primary Examiner.

P. E. ANDERSON, Assistant Examiner.

Notice of Adverse Decision in Interference In Interference No. 95,959 involving Patent No. 3

RESIN CURING, final judgment adverse to the pate 8, 1968, as to claims 1-3, 5, 6, 7, and 8.

[Oficial G ntee was rendered July azetz e September 24, 1.968.]

,28l,5l5, R. D. Schmitz, 

1. THE PROCESS OF CURING A RESIN WHICH CAN ONLY BE CURED AT ELEVATED TEMPERATURES AND WHICH CURES AT FASTER RATES AT ELEVATED TEMPERATURES THAN AT ROOM TEMPERATURE COMPRISING BRINGING THE RESIN INTO INTIMATE EMBEDDED CONTACT WITH A FINELY DIVIDED, HEATED, SOLID CHEMICALLY INERT MATERIAL. 